C-RAN: the Road Towards Green Radio Access Network

Clark Chen / 陈奎林

China Mobile Research Institute

August, 2012

Agenda of Today

Why C-RAN is Important to Mobile Operators? - Cost, performance and industry trends

What’s the Challenge of Operators today? - The mobile internet traffic challenge

How do We Drive C-RAN in the Future? - Joint requirement, R&D, and deployment

Operator still has Challenges in Mobile Internet Era

Power consuming surging as BS number increases

CAPEX and OPEX associated with cell sites Fast increasing data traffic but slow revenue growth

A green evaluation path is need for Radio Access Network deployment and operation, to achieve high capacity, high power efficiency and low cost

Dynamic network load challenge

BS cell site is the major source of power consumption of China Mobile

Big gets Bigger, Small gets Smaller

RRU

RRU

RRU

RRU

RRU

RRU

RRU

BBU Pool

BBU BBU

BBU

Nano-cell/Femto-cell that has WiFi and LTE carrier for

hotspot and indoor

C-RAN system that support 1000+ LTE carriers and cover

10+ kilometer radius area

Tradition Macro Cell supports 12~36 GSM carriers

Covers 0.2~2km radius

Indoor/hotspot coverage

…

RRU

RRU

RRU

RRU

RRU

RRU

RRU

Virtual BS Pool

Distributed RRU

High bandwidth

optical transport

network

Real-time Cloud

for centralized

processing

…

Centralized Control and/or Processing Centralized processing

resource pool that can support 10~1000 cells

Collaborative Radio Multi-cell Joint scheduling

and processing

Real-Time Cloud Target to Open IT platform Consolidate the processing

resource into a Cloud Flexible multi-standard

operation and migration

Clean System Target Less power consuming Lower OPEX Fast system roll-out

Network Implementation will be the Next Focus C-RAN: Centralized, Collaborative, Cloud, and Clean System

Agenda of Today

How do We Drive C-RAN in the Future? - Joint requirement, R&D, and application

Why C-RAN is Important to Mobile Operators? - Cost, performance and industry trends

What’s the Challenge of Operators today? - The mobile internet traffic challenge

Centralized Deployment Helps Cost Structure

Lower CAPEX and OPEX

Save up to 15% CAPEX and 50% OPEX compared to distributed BTS 3G network*

0 100 200 300

Faster system roll out

Due to simpler remote radio site, system roll out can save up to 1/3 the time*

Lower energy consumption

Save up to 71% of power compared to traditional RAN system*

*Source: Base on China Mobile research on commercial networks

Collaborative Radio Further Improves Performance

1.9 2.542.47

5.46

2.81

6.15

3.01

6.58

0

2

4

6

8

2Tx (X)/2Rx 8Tx(XXXX)/2Rx

Ave. cell spectrum efficiency (bps/Hz)

SU-MIMO

MU-MIMO

0.0560.098

0.047

0.1830.0780.227

0.101

0.266

0

0.1

0.2

0.3

2Tx (X)/2Rx 8Tx(XXXX)/2Rx

Cell-edge spectrum efficiency (bps/Hz)

SU-MIMO

MU-MIMO

*Source: China Mobile simulation results on 3GPP assumptions

Interference has become the major limit

E.g. in big cities of China, the distance between BTS is just 100~200m, and interference become a serious challenge

Collaborative Radio is the Ultimate Solution

Change the interference to useful signals

Make better use of TDD channel reciprocity

IT Technology Evolution

• Huge IDC, advanced server network technology

• Cheap device, high BW, high reliability

• Soft switch has replaced traditional switch system

• 40 servers = 10M line fixed-line switch

• Open platform replaced proprietary platform

• x86 systems replaced dedicated servers

Traditional Switch Solution

• Proprietary hardware + embedded software

• ASIC, 8086,

• Very expensive (used to be)

• 2000 Yuan per line in 1990s

• High OPEX, and low flexibility

• Dedicated equipment room, closed S/W env.

Today’s Soft-switch Solution

• Standard IT hardware + software switch

• x86 platform, standard OS

• Low cost

• Far below 100 Yuan per line

• Simple OPEX, high flexibility

• 10 times less room occupation with <30%

energy consumption (*)

Support 500M user with

distributed P2P network on

standard IT platform

IT Technology Helps Telecom Evolution

Agenda of Today

How do We Drive C-RAN in the Future? - Joint requirement, R&D, and deployment

Why C-RAN is Important to Mobile Operators? - Cost, performance and industry trends

What’s the Challenge of Operators today? - The mobile internet traffic challenge

Joint R&D on C-RAN with TEM/IT Partners - IT based wireless platform opens the door to more flexible system

• CMRI and Huawei, Intel, IBM, and ZTE have

built two independent C-RAN PoC which

realized LTE PHY processing in real time

• 2G/3G/4G RAT verified on IT platform

Successful OTA demo in 2011 ITU Telecom

World, Geneva

• ALU, Agilent and others are joining

2G/3G/4G

RRU

CPRI

Today: Tri-mode BBU on IT Platform

2G/3G terminal

4G test terminal

Future: Large Scale, Real Time BBU Pool

• Build telecom grade reliable (99.999%) real-

time Cloud with cheap building blocks with

relatively low reliability (99.9%)

• Scalable, Reliable, and Cost Effective system

Changsha C-RAN/2G Network

• 10 sites, 247 GSM/EDGE carriers

• Dynamic resource allocation

C-RAN has shown advantages in places with fiber:

Suitable for these deployment scenarios:

• HetNet deployment in the following areas:

• Urban city’s business street

• University campus

• Suburb deployment

Changchun 2G Network

• Dense city – college campus case

• 5 centralize device room, 98 RRHs

• 30,000 subscribers in 3 km2

C-RAN Trials in Commercial Networks - for dense urban city, business street and campus; well suit for HetNet deployment

Zhuhai C-RAN/3G Network

• First in China Mobile network

• 18 sites first, expend to 100 sites

Zhuhai Dongguan

Zhaotong

Changsha

Baoding

Changchun

Guangzhou

Beijing

Guangzhou C-RAN

3G/4G Dual Mode

• First dual-mode case

• Same BBU-RRU for

3G/4G network

• 12 sites, 36 LTE

20MHz carriers

Centralization Deployment First step of C-RAN centralization trialed in 2G/3G in 7 city’s networks

2010 2011 2012

Near Term:

Address the fiber

resource and

management challenge

Mid-Term:

Address the SDR and

Collaborative Radio

challenge

Long Term:

Address the real-time

cloud challenge

Multi-mode and Collaborative Radio Drive the industry to do research and prototype:

SDR on open platform, Collaborative Radio

Virtual BTS on real-time Cloud Large scale BBU pool Real-time virtualization System OS, API standardization

C-RAN Research Data traffic analysis BBU pool research

Expend C-RAN to 2G/3G/4G networks

Drive CoMP research and field trial, pre-commercial product

Commercial product development

We are here

We are Driving C-RAN R&D as Planned

2013 2014

Industry Alliance to Build C-RAN Eco-system - Global industry collaboration

Collaboration with KT

and SKT

NGMN C-RAN Project

drive by CMCC

Sweden

Signed C-RAN MoU

with Ericsson and NSN

Germany

Signed C-RAN

MoU with Orange

Franch

Close collaboration

with Huawei and ZTE

Cooperate-level strategy

collaboration on C-RAN

CMRI-IBM signed MoU on

multi-mode SDR PoC

Strategy collaboration

with Alcatel-Lucent

Korean China

U.S.A.

Call for Joint Exploration!

Thank you Thank You